Wifi setup for conference centre / congestion issues?

[nell1]

Hi All, scenario is below:

Small Sized exhibition hall with approx 100-200 Wifi users surfing internet and downloading reasonably bandwidth heavy data.
Needs to be a seemless roaming experience for the user

What immediately concerns me about this is the very real potential for wifi congestion with the user experiencing painfully slow browsing/download speeds.

Am I also right in thinking that in using the 802.11g protocol I really only have 3 channels to play with in such a confined place? Would having access points on different channels but same SSID's increase speed but maintain the seemless roaming experience for the user? I had thought that same channels were needed for seemless roaming.

Positioning could also be an important factor as the venue is not allowing us to mount the AP's on the walls, instead we have to place on tables around the room. How much difference does anyone think this will make coverage/speed wise?

Would really appreciate some advice/help if anyone can spare.

Many thanks,

Nell1

 

[jdeisenm]

What is your internet pipe? How many ap's? Likey, that will be the bottleneck and NOT your wifi speed. Do place your ap's on channel's 1,6,11. If you have a lot of ap's. Draw hexagons on your conference room map and put the ap's on the points of the hexagon(s). Make sure the antennas stay vertical. You might have better overall throughput if you leave the ap's on B as a B laptop will bring the speed of all devices down anyway.

 

[nell1]

Pipe is 8mb Down and 2mb Up. Looking at 4 - 5 AP's.

AP's on different Channels but same SSID will experience seemless roaming won't they?

Someone else advised me to exclude the b protcol and just use g? If left on the lower speed of b will that reduce the congestion?

Many thanks jdeisenm!!

Nell1

 

[dput]

By eliminating the B devices, you will eliminate the ability for many older devices and for most PDA's to connect to your network. If you are concerned about speed and can control what devices people are using, turning off the B might make some sense, if you are trying to open up connectivity to a variety of people, I would leave B on.

Dan

 

[jdeisenm]

roaming is mostly a function of the pc wireless nic, older intel 2200 drivers (common in dell's, thinkpad and toshiba) would not roam make sure driver date is year 2005 or later

 

[vipergg]

You may run into problems anyway if you have that many users using them at the same time . Even if you restricted it to G you will never get 54 meg out of it . Also something else important to remember is that wireless is a shared medium and everyone shares the available bandwidth just like an old hub . If you get utilization above 30-40% things are going to get slow . The farther away you are from the AP the slower the connections will be , anyone running a B adaptor will bring everyone down to "B" speeds .

 

[nell1]

Vipergg,

"Everyone running a B adaptor will bring everyone down to "B" speeds"....

I was under the impression that people could connect to the same AP at different speeds depending on their adaptors and the capabilities of the AP?

 

[tmt7734]

With this amount of users I would suggest going with a Wireless Mesh setup. Basically a mesh uses 802.11A radios as a backhaul creating a virtual ehternet switch via wireless, then B/G radios for client access. You can get (cheaper) units with just the 802.11A radios and an Ethernet port to connect your own cheap B/G AP's to or (more expensive) units with up to 4 radios inside, 2 for backhaul 2 for client AP access. I have a portable setup with 500+ users and performance is very good. Roaming from AP to AP switching times under 50ms, which is unoticable for VOIP aps. With this setup you can have all of your AP's on the same SSID with differnt channels. With the multiple radio models you can have the b/g client radio transmit up to 16 SSID's which will give you a lot of flexiblt. Some of the manufactuers are Strix, Firetide, Meshdynamics, and Tropos. Do a google search and you can find more info.

 

[nell1]

Unfortunately I don't think I have enough time now to explore the mesh route for this event, however definately going to look into. Think I am gonna go with restriction to b protocol and try and limit to three channels. Hopefully they have over estimated attendance / concurrent connections.

Many thanks for all your help chaps!!